The objective of the proposed study is to construct "expression" cDNA, "exon" DNA, and genomic DNA libraries of Schistosoma mansoni, a causative agent of human schistosomiasis, and to assay attendant cloning vehicles for production of parasite-encoded proteins reactive with (1) antisera obtained from naturally-infected human donors, (2) antisera from rats vaccinated with highly-irradiated cercariae, and (3) monoclonal antibodies possessing known biological activity. The intent is to assess the feasibility of applying recombinant DNA techniques towards the isolation, in preparative amounts, of schistosome-related proteins having potential immunoprophylactic and/or diagnostic value; such might otherwise prove difficult to obtain. Antigens having potential diagnostic value will be identified by assaying positive clones with a variety of antisera obtained from patients harboring schistosome infection (to assess the generality of the response) and from uninfected donors living in endemic areas (to assess the specificity of the response). Discrimination of potential protective antigens will involve assay of clones reactive against rat antiserum (which displays strong schistosomidal activity) with monoclonal antibodies capable of conferring significant resistance to uninfected recipients, or possessing strong activity in promoting in vitro, cell-mediated cytotoxic damage to schistosomulae. Antigens not identifiable with available monoclonal antibody will be used to produce monospecific antibody in uninfected rats; this antibody will be used to determine, by indirect immunofluorescent assay of young schistosomulae, whether the corresponding antigen is a surface component. Reagents derived during the course of this study (i.e. stage-specific cDNAs and cDNAs identified with heterologous actin, tubulin, and collagen probes) will be used to dissect aspects of the organization of the schistosome genome. Related information should prove useful towards defining future, less generalized strategies for cloning schistosome sequences of interest.